Tetrahedral [Sb(AuMe)(4)](3−) Occurring in Multimetallic Cluster Syntheses: About the Structure‐Directing Role of Methyl Groups

The anion of [K(crypt‐222)](3)[Sb(AuMe)(4)]⋅py (1; crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane; py=pyridine) represents a rare example of a homoleptic heavy p‐block metal atom being surrounded by four free‐standing transition metal complex fragments, and the third example for a corresponding Sb compound. In contrast to all reported complexes of this type, the transition metal atoms possess twofold coordination only, hence the complex as a whole does not exhibit significant steric shielding or further linkage of the metal atoms. This is reflected in a high flexibility, as confirmed by slight deviations from a tetrahedral coordination of the Sb atom in the crystal and soft vibrational modes. An alternative pyramidal conformer, observed for a related arsenic compound with terminal phosphine ligands, is apparently disfavored owing to electron correlation effects. The compound is formed in a reaction that in another solvent or at other reactant concentrations yields salts of ternary cluster anions. By a combined experimental and theoretical study of different reaction conditions and previously unidentified side‐products, we provide insight into multimetallic cluster synthesis reactions.